The purpose of this project is to take empirically supported, clinic-based treatment programs for child oppositional and conduct disorders (ODD/CD) and evaluate their short- and long-term efficacy as school-based early intervention programs for preventing ODD/CD, one of the most important behavioral predictors of substance abuse and delinquency. These school-based interventions for children ages 5 to 7 years are three carefully integrated packages that maximize consistency and follow-through in the home and the school. The intervention enhances children's protective factors (i.e., academic and social competence) and reduces risk factors (i.e., aggressive behavior and low school involvement) by: (1) teacher training, strengthening teacher competencies in classroom management and collaboration with parents: and (2) child training, implementation of the Dinosaur Social Skills and Problem-Solving Curriculum (delivered in the classroom by trained teachers); and (3) parent training, strengthening discipline competencies and fostering school involvement. The teacher and child training programs (CR) will be offered as a universal intervention to all kindergarten and 1st grade children in randomly assigned intervention schools. In addition, a randomly selected subset of parents of higher-risk (top 1/3 aggressive behavior) children from CR schools will be offered the indicated parent program (PT). The intervention will span kindergarten and 1st grade. Outcome will be measured by comparing intervention (CR or CR + PT); control children in terms of conduct problems, child social and academic skills, parent competencies and school involvement, teacher classroom management skills, and classroom environment. Multiple agents and assessment methods will be used including independent classroom observations of teacher-child and peer-child as well as teacher reports of aggression and social competence. Additionally, for indicated children, home observations of parenting interactions and child noncompliance and conduct problems will be assessed. Follow-up assessments will be conducted at the end of kindergarten and each year through grade three.